Cab battery problem

Nov 26, 2018
Hi, can anyone help?
Own a Ducato based Ace Airstream.
Returned from trip to France in September, after 2 weeks tried to use motorhome to find that the cab battery was totally flat. As it was of unknown vintage, bought brand new Yuasa Silver 5000 battery. Fitted this, all appeared fine.
Tried to unlock using remote 3-4 weeks later (not used in between), not enough power to even unlock doors, battery totally flat.
Nothing left turned on, so what can be draining battery?
Any ideas?


Sep 20, 2011

I believe the Ace Airstrem model was marketef from 2007 to 2009, but it might be useful to know how old your motorhome is.

If you GOOGLE-search using “Ducato flat battery” as the search-term, you will retrieve plenty of complaints regarding this issue and motorhomes.
Assuming your motorhome is around 10 years old, you might want to start by replacing its earth-strap.
There’s no particular reason to think a deteriorated earth-strap will have resulted in your new starter-battery going flat, but received wisdom is that - if the earth-strap has deteriorated - there is plenty of scope for electrical problems as a consequence. (Basically, replacing the earth-strap may well have no beneficial effect whatsoever on your battery-related issue, but it just might do some good and it shouldn’t cause any harm.)

From what you’ve said, even with the age-unknown battery, it seems that your Airstream could stand idle for 3-4 weeks without the battery receiving charge and there would still be enough life in the battery to start the motorhome’s motor.

When a Ducato is standing idle its starter battery will be providing a continuous 12V supply to the vehicle’s electronics and to any add-ons that the battery might be powering (eg. the radio’s memory and an alarm as Alan has suggested). But that will also have happened when the old battery was fitted.

There are plenty of on-line comments from owners of 2006-2014 Ducato-based motorhomes, saying that, if the vehicle stands idle, its starter battery will flatten in much less than 3 weeks if the battery is not recharged.

There is the (small) possibility that your Yuasa battery is faulty, but I suggest you do the following (You’d need a digital multimeter):

1: Charge the starter battery 100%. (You might need to use a separate charger to do this.)

2: Take voltage readings on a daily basis to check the battery’s state of charge and give you a (rough) idea of its discharge rate.

3.: If it becomes plain that the battery is discharging unusually quickly, you would need to identify the culprit, which would mean taking amperage readings to establish which of the things the battery is powering is pulling down its charge-state.

If you don’t feel up to fiddling about with your motorhome’s electrics, you might want to get the problem investigated by an auto-electrician who is familiar with motorhomes.

Are you absolutely certain that, when your Airstream is standing idle, there is nothing turned on that will be powered by the starter battery and can be switched off? If, for example, you normally have an alarm operating, if you switched off the alarm as an experiment and the battery did not discharge rapidly, it would be reasonable to assume that the alarm system was causing the battery to lose its charge.